Abstract
BACKGROUND: Although the significance of apolipoprotein E4 (Apo E4) in Alzheimer's disease (AD) has been well established in Caucasian populations, its role in determining the rate of cognitive decline in other ethnic groups has yet to be determined. This study examined the two-year progression of cognitive decline and its association with Apo E4 allelic status in a group of Chinese elderly subjects with AD. METHOD: One hundred and four Chinese subjects with mild and moderate AD as assessed by the Clinical Dementia Rating (CDR 1 and 2) were followed up at a mean (SD) duration of 22.53 (5.21) months. The rate of cognitive decline and its association with Apo E4 allelic status was evaluated RESULTS: At follow-up, 74 (73 percent) subjects were reassessed. Forty-nine remained stable at the same CDR and 25 had deteriorated. The mean (SD) deterioration in the Mini-Mental State Examination (MMSE) was 2.52 (4.38) and in the Mattis Dementia Rating Scale (DRS) was 9.03 (14.98) (paired t-test, p < 0. 001). There was no significant difference in the baseline MMSE and DRS scores between the "stable", "deteriorated", or "deceased" groups. Mildly demented subjects with the Apo E4 allele were more likely to have deteriorated to a more severe CDR than subjects without the Apo E4 allele (Pearson chi2 = 5.72, df 1, p = 0.017, Odds ratio = 6.3, CI 1.3 to 30.53). CONCLUSION: The presence of the Apo E4 allele may influence the rate of cognitive deterioration, particularly in subjects with mild AD.